![Dotted Decimal Notation
• IP addresses are written in a so-called dotted
decimal notation
• Each byte is identified by a decimal number in the
range [0..255]:
10000000 10001111 10001001 10010000
1st Byte 2nd Byte 3rd Byte 4th Byte
= 128 = 143 = 137 = 144
Fig.2 128.143.137.144
-- 7](https://image.slidesharecdn.com/ipaddressconcepts-121016114750-phpapp02/85/Ip-address-concepts-7-320.jpg)
Ip address concepts
- 1. Sub Topic : IP Addressing Concepts Teaching Aids : Diagrams, Animations -- 1
- 2. Recap In the previous class, you have learnt about • Leased line, DSL and Cable MODEM -- 2
- 3. Objectives On completion of this period, you will be able to know about • What is an IP Address? • What is network prefix and host number? • What is Internet address? • What is sub-netting and no sub-netting? -- 3
- 4. What is an IP Address? • Internet identifier including information about how to reach a network location (via the Internet routing system) • IPv4: 32-bit number. Written in Dotted Decimal Notation 205.150.58.7. – 4 billion different host addresses • IPv6: 128-bit number. Written in Hex Decimal Notation 2001:0503:0C27:0000:0000:0000:0000:0000 – 16 billion network addresses -- 4
- 5. IP Addresses 32 bits version header Type of Service/TOS Total Length (in bytes) (4 bits) length (8 bits) (16 bits) flags Identification (16 bits) Fragment Offset (13 bits) (3 bits) TTL Time-to-Live Protocol Header Checksum (16 bits) (8 bits) (8 bits) Source IP address (32 bits) Destination IP address (32 bits) Ethernet Header IP Header TCP Header Application data Ethernet Trailer Ethernet frame Fig .1 -- 5
- 6. Network Prefix and Host Number •The network prefix identifies a network and the host number identifies a specific host (actually, interface on the network) network prefix host number •How do we know how long the network prefix is? –Before 1993: The network prefix is implicitly defined (see class-based addressing) –After 1993: The network prefix is indicated by a net mask -- 6
- 7. Dotted Decimal Notation • IP addresses are written in a so-called dotted decimal notation • Each byte is identified by a decimal number in the range [0..255]: 10000000 10001111 10001001 10010000 1st Byte 2nd Byte 3rd Byte 4th Byte = 128 = 143 = 137 = 144 Fig.2 128.143.137.144 -- 7
- 8. IP Address • Every interface have a unique Internet address (IP address) • Consist of 2 parts – network id and host id • 32-bit address • 5 Classes –A – 0.0.0.0 to 127.255.255.255 (224 nodes) –B – 128.0.0.0 to 191.255.255.255 (216 nodes) –C – 192.0.0.0 to 223.255.255.255 (28 nodes) –D – 224.0.0.0 to 239.255.255.255 –E – 240.0.0.0 to 247.255.255.255 -- 8
- 9. IP Address contd…. • When Internet addresses were standardized (early 1980s), the Internet address space was divided up into classes • Class A: Network prefix is 8 bits long • Class B: Network prefix is 16 bits long • Class C: Network prefix is 24 bits long • Each IP address contained a key which identifies the class • Class A: IP address starts with “0” • Class B: IP address starts with “10” • Class C: IP address starts with “110” -- 9
- 10. IP address contd… bit # 0 1 7 8 31 Class A 0 Network Prefix Host Number 8 bits 24 bits bit # 0 1 2 15 16 31 Class B 10 network id host Network Prefix Host Number 16 bits 16 bits bit # 0 1 2 3 23 24 31 Class C 110 network id host Network Prefix Host Number 24 bits 8 bits -- 10
- 11. IP Address contd… bit # 0 1 2 3 4 31 Clas D 1110 multicast group id bit # 0 1 2 3 4 5 31 Clas E 11110 (reserved for future use) Fig .4 -- 11
- 12. Special IP Address •All 0’s is reserved to refer to a network number •All 1’s is reserved to refer to a broadcast address -- 12
- 13. Sub-netting • Class A and B has too many nodes • Network is divided to sub-network • Improve network performance • Indicate by subnet mask -- 13
- 14. No Sub-netting • All hosts think that the other hosts are on the same network 128.143.137.32/16 128.143.137.144/16 128.143.71.21/16 128.143.71.201/16 subnetmask: 255.255.0.0 subnetmask: 255.255.0.0 subnetmask: 255.255.0.0 subnetmask: 255.255.0.0 128.143.70.0/16 Fig .5 -- 14
- 15. With Sub-netting • Hosts with same extended network prefix belong to the same network 128.143.137.32/24 128.143.137.144/24 128.143.71.21/24 128.143.71.201/24 subnetmask: 255.255.255.0 subnetmask: 255.255.255.0 subnetmask: 255.255.255.0 subnetmask: 255.255.255.0 128.143.137.0/24 128.143.71.0/24 Subnet Subnet 128.143.0.0/16 Fig .6 -- 15
- 16. Summary In this class, you have learnt about • At the network layer, a global identification system that uniquely identifies every host and router is necessary for delivery of packet from host –to-host • An IP v4 address is 32 bit long and uniquely and universally define a host or router on the Internet -- 16
- 17. Summary contd…… • In classfull adressing,the portion of IP address that identifies the network is called netid • In classfull adressing,the portion of IP address that identifies the host or router on the network is called the hostid -- 17
- 18. Summary contd.. • An IP address defines a device’s connection to a network • There are five classes in IPv4 addresses • Classes A, B and C differ in the no. of host allowed per network • Class D is for multicasting and class E is reserved -- 18
- 19. Quiz 1. IP version 4 is of ______ bits (a) 32 (b) 48 (c) 24 (d) None of the above -- 19
- 20. Quiz 2. In IP addressing there are ___ classes (a) 5 (b) 4 (c) 6 (d) None of the above -- 20
- 21. Frequently Asked Questions 1. Discuss the concepts of IP addressing 2. Describe the classes of IP version 4 addressing 3. Write a short note on default gate ways 21